In general, endoscopic imaging systems allow the evaluation of animal and human internal organs. Endoscopes can consist of at least one of the following components, a rigid or flexible tube, a light delivery system, a fluid delivery and recovery system, an air delivery and recovery system, a lens system, an eyepiece, a high pixel-count color CCD or imaging transmission system, graphical display unit (monitor), and/or accessory channel(s) to allow use of devices for manipulation, sampling or imaging of target lesions.
The endoscope may be inserted into any natural orifice of the animal or human including the nares, ears, mouth, biliary tract, pancreatic duct, ostomy, urinary tract, vagina, uterus, fallopian tubes, anus and/or any opening produced by procedures employing an incision or puncture into an internal body cavity (craniotomy, thoracotomy, mediastinotomy, laparotomy or arthrotomy). While currently available endoscopes are capable of evaluating target structures by the obligatory forward or other directional field of view obtained by current light delivery and lens systems, in some medical applications this design increases the risk for missed detection of important areas of interest. As a result, there is a need for multi-directional visualization.
Colonoscopy is widely considered the gold standard for detecting mucosal abnormalities in the human colon, and the preferred technique for removal of many non-invasive lesions requires biopsy, polypectomy or endoscopic resection. There have been well-documented limitations related to the practice of colonoscopy with traditional endoscopic instruments. Because most colon cancers are believed to arise from abnormal colon tissue, adenomas, the detection and removal of adenomatous polyps have been recommended for the prevention of future colon cancers. (See, e.g., ref. 1). Missed polyps or cancers have been one of these unfortunate limitations. (See, e.g., refs. 2-4). Although there are additional factors associated with the risks of missing mucosal lesions such as, a patient's colonic anatomy, patient comfort during an endoscopic procedure and the quality of bowel preparation, it has been well established by other investigators, that the location of mucosal abnormalities is highly associated with failure of identification. (See, e.g., ref. 4).
Prior groups have investigated several approaches to attempt to demonstrate an improvement in the diagnostic yield of a colonoscopic procedure by altering or increasing the conventional forward fields of view. Unfortunately these studies did not demonstrate a significant increase in adenoma detection. (See, e.g., refs. 5-7). Nevertheless, the uses of a transparent cap that does not change or improve the field of view placed on the distal aspect of colonoscopes have demonstrated great promise in improving the effectiveness of colonoscopy (see, e.g., refs. 8-11) and adenoma detection (see, e.g., ref. 12), however the use of these devices are still associated with a significant adenoma miss rate. (See, e.g., ref. 13).
Other researchers have attempted to improve the adenoma detection rate established with the use of a conventional endoscopic system by increasing the total field of view during a colonoscopy by coupling the traditional endoscope with an auxiliary imaging device, placed within the accessory channel, to provide a continuous retrograde view of the target organ via the accessory channel. (See, e.g., ref. 14). While this auxiliary imaging device provides a continuous retrograde field of view used in combination with traditional forward viewing endoscopes, it requires the use of an accessory channel of the endoscope. This becomes an important factor during colonoscopy, if used with a standard single channel colonoscope, due to the necessity to remove the auxiliary imaging device to allow for the use of an appropriate auxiliary sampling or retrieval instrument to biopsy, resect and retrieve specimens removed from the organ being investigated. This additional equipment has been shown in a prospective, multicenter, randomized, controlled trial to decrease the relative risk of missing polyps and adenomas but was also shown to have a statistically significant increase in the mean total procedure times.15 Auxiliary endoscopic devices placed within the auxiliary channel of the endoscope have the further disadvantage that they require an additional endoscope, which increases complexity, ease of use, and cost of the overall procedure.
Thus, there is a need to address at least some of the issues and/or deficiencies described herein above.